They're skipping school, they're excluded from sports and they're shunned from places of worship -- once a month, at least, when they're menstruating.
For many women and girls in India, even talking about periods is taboo, and a lack of access to sanitary products means life comes to a standstill for a few days every month.
The Myna Mahila Foundation is trying to change that. The organization employs 15 local women from Mumbai slums to make sanitary pads, while another 50 women distribute them door to door in the slums. The model means stable employment for the workers and easy, affordable access to pads for people in the community.
Speaking to CNN on Monday, marking Menstrual Hygiene Day, the foundation's co-founder Suhani Jalota listed the many reasons women and girls fail to get such essential items.
"There's a whole bunch of different factors here where women don't have access to these products -- they don't even have knowledge of these products. There is a lot of stigma around it, there's a lack of facilities and infrastructure at schools," she said, explaining that some schools did not have functional toilets.
Girls even drop out of school during puberty because they simply don't have the means to manage their periods.
Meghan, Duchess of Sussex, gives Myna a boost
Interest in Myna Mahila has grown since Britain's newly married royal couple, Harry, the Duke of Sussex, and Meghan, the Duchess of Sussex, included the organization on their list of charities to donate to in lieu of wedding gifts.
The Duchess, who has spoken out on feminist issues and women's empowerment, had visited the organization in India, and was photographed in a sari as she met with the women working there.
Her involvement has helped spread awareness of menstrual hygiene across India and given the movement a stamp of approval, Jalota said.
Tackling stigma is a major challenge, particularly when it comes to talking about periods between genders.
"If you were to buy a packet of sanitary napkins today, you have to go to a chemist shop or a medical store, which is manned by men -- male shopkeepers, and there are male bystanders, there are male customers -- and there's this one woman there who's announcing that she wants a packet of pads, implying that she has her period. So the male shopkeeper kind of doesn't even look at her straight," she explained.
Out of shame, many women use traditional rags and wash and dry them discreetly, storing them in damp and unhygienic conditions.
Shame aside, more than 40% of women between the ages of 15 and 24 in India have no access to sanitary products in the first place, according to the India National Family Health Survey.
Jalota said that she and Myna Mahila's co-founders started the organization with the hope of encouraging women to talk about the things they were most afraid to talk about. In fact, the charity's name comes from the "chatty" myna bird.
"We really started this movement around menstrual hygiene first because we feel that it's a very tangible way of tackling empowerment," she said.
She added that they found women in the communities where they worked had powerful voices, but they were being treated as invisible. They wanted to encourage more confidence in women to determine their own lives.
"If women started to consider themselves to be more important, then slowly it would start conversations around domestic violence, and sexual assault and menstrual hygiene, things that women were currently shying away from."